Expansion And Intercalation Mechanism Of Montmorillonite And Construction Of Novel Fluorescent Functional Material

Montmorillonite(MMT)was a type of aluminosilicate non-metallic nanomineral with a layered structure which has a two-dimensional nanosheet structure and cation exchange capacity.It is widely used in various fields due to its swelling property,water absorption,ion exchange property,structure and function controlable,cheap,easy to obtain,and it is environment friendly.However,the lack of systematic and in-depth research on the organic intercalation and stripping mechanism of montmorillonite has seriously affected the development and application of montmorillonite functional novel materials.Montmorillonite was the main study object in this paper.The mechanism of organic cation-intercalated and stripping montmorillonite was discussed through the systematic study of various factors affecting organic intercalation.The development and application of novel materials with montmorillonite function were explored based on the theory.The stripping of some kind of montmorillonite minerals were first discussed in the thesis which found hectorite has the best exfoliation effect.Taking hectorite as the representative of montmorillonite minerals,the process of its expansion stripping and dehydration was studied.The results showed that the thickness of hectorite can be less than 10 nm when the peeling concentration was low enough(1 mg/L).The addition of CTAB to the hectorite stripping system tended to give a better peeling effect.The thickness of hectorite increased gradually in the dying process which implied the re-stack of hectrorite.The speed of hectrorite re-stack slowed down after the addition of CTAB which indicating the resistance of the aoganic cation.Based on the above analysis the model of montmorillonite mineral stripping was put forward.Based on mechanism of montmorillonite exfoliation and intercalation,lucigenin/montmorillonite luminescent composite was constructed,where fluorescent quenching has been restrained and luminescence is greatly enhanced.The effect of different conditions on the luminescent properties was revealed through the experiment and an optimum condition for higher luminescent performance has been obtained.The composite material of lucigenin/montmorillonite fluorescent aerogel was ultilized as the detection of phenol with detectionlimits of 0.35 ppb.In this part study,another fluorescent probe 7-amino-4-methylcoumarin was successfully intercalated into the interlayer space of montmorillonite(MMT)as guest molecule,which resulted in significant inhibition in fluorescence quenching.With its enhanced fluorescent property,the composite was fabricated into a film with chitosan to detect Cr(VI)in water.Cr(VI)in aqueous solution can be detected with a detection limit of 5 μmol/L.